Photographic film for color photography



y Sept. 21 1926.

R. BERTHON PHOTOGRAPHIC FILM .FOR COLOR PHOTOGRAPHY Filed Jan. 10 1923 one E m5 m We Mum/.MA OVVZ vm ,H

' ber, must vary according to normal thickne of 0.1 2 millimetelg the standard net must contain, instead of 625 nipples, X 12.

or 2500 nipples per square millimeter, this 'number' allowing considerable latitude both above described presents a further invaluable advantage over simple refraction nets. All these nets com rise microscopic lenses whose diameter, being a function of their number per unit of surface, isof the same order of magnitude as the definition of the project' o jectives, say 1/25 linear millinieter an less. It follows that the proofs "obtained with these nets donot allow Vtheir reticular texture to beA noticed on projection and, for the same reason, that these proofs can be reproduced by projection either on a similar scale or on a modified scale, without their nets becoming' reeptible and causing rain, a defect which can be eliminated in nets of the 225 type only bnmeans of com licated o tical devices or -crossing invo` ving mato ing of the most intricate character.

It will be derstood from theforegoing that the invention resides in the fact that, due to the increase in the number of microscopic lenses or nipples'per square millimeter, a diifracting action is obtained. It is the operation of the iilm consequent upon thisdiifraction which constitutes the true characteristic of the invention; and it is apparent that a result inferior to that produced by increasing the number of nipples, but nevertheless important, can be obtained with films of the 225 type by providing on the photographic support an opaque net which limits the diameter of each nipple so as to reduce it sulliciently to produce the desired diiraction effect.

As further explanatory of the foregoing and as illustrating the application of the invention to color photography, for which it is primaril designed, reference will now be ymade to e accompanying drawings, in which: 1 d1 i h igure is a 'tic view s ow ing the diffraction produced when a trichromatc selecting screen is used in the objective.

as indicated bythe white parts of the images lg 23.5.12 sommi s.

are wing u of the s formed on the sensi'- yer of the film before and after an obect has been photggraphed. 'N li 5isadi owingthelmafter deveipment an inversion.

Fig. 6 is a face view of the support or for the layer of sensitive emulsion. In said drawings, 6, 61 and 6z (Fig. 1) 1l indicate the three parts or members of the objective of a photographic camera, and 7 the tri-chromatic selecting screen referred. to, said screen being interposed between( the members 6 and 61 and consisting of a glass 80 disk banded or zoned in the three grimary colors blue, green and red. The yer of sensitive pancliromatic emulsion on the film is indicated at 8, and the support or backing at k8', the latter itsouter face embossed with a network of ine lenticular elements or nipples 82 of the character above described. The image 71 of the screen 7 is formed on. the layer 8 behind ca ch of the nipples 8*, as indicated in 90 If a blue object is photographed, the light rays will pass through theblue zone only of the screen or iilter produce an impression in black on the lyer behind each nipple, as indicated by the-across-hatched arts of the images 7 in Fig. 4.- After the has been develo and inverted, the cross-hatched parts will become transparent,

7' in Fig. 5, al1 the rest of the film remaining opaque. -In ro'ecting, the procedure is. reversed: the lig t ing free to pass only through the transparent parts, luminous ncils will be formed which pass t ugh all the corresponding parts of the selecting screen and the object will appear v in blue on the projection The same applies equally to all the intermediate colors; the yellow rays, for instance, will pass through the green and red zones.

I claim as my invention 1. A photographic film for color photography, embodying a transparent support or acking, and a layer of sensitive emulsion thereon; said support having its outer face formed with a net of microscopic lenticulai elements comprising above 500 suchv elements per square millimeter so Yas to produce the phenomenon of diii'raction in addiion that ofY refraction; substantially as escri 2. A hotographic film, according to claim 1, in w -ch the lenticular elements on the transparent backing number more than 1000 l. per uare millimeter; substantially as descri In testimony whereof Iallixed my signature.

RODOLPHE BERTHON.

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